The present invention relates to a substantially flat end wall of thermoplastic material that forms the lid of a liquid pack. Included is a pouring means which is disposed within the outside contour of an outer first plane of the pack and which comprises an opening flap portion which closes a pouring opening and which is mounted to a hinge. A handle is secured to the opening flap portion, wherein the opening flap portion is connected by way of an endless weakening line to the wall of the lid. The pouring means further comprises a collar which is disposed at the periphery of the lid at an inwardly displaced position, for mounting to a side wall of the pack.
A lid or cover of this kind is disclosed in German Offenlegungschrift No. 31 39 780, wherein a liquid pack comprises tubular side walls of coated cardboard and end walls which are mounted to the ends of the tube. While one end wall, representing the bottom, is square or rectangular and is of the configuration referred to as a block bottom, the end wall forming the lid or cover of the pack comprises thermoplastic material without any carrier material. The plastics lid is ejected on to the side walls along the outside edge of the lid and has a pouring means which can be folded inwardly of the outside contour of the pack, for transportation purposes.
As is known in the art, attempts have been made to provide a suitable lid which is fluid-tight and easy to open, using simple production tools. The opening means in such a lid is disposed at the center thereof because it was considered particularly desirable for the lid or cover to have an upwardly convergently tapering wall leaving a central opening, with a centrally disposed, upwardly projection spout edge and a closure means secured thereto. This view was taken in the belief that the tools and in particular the injection molding mold for such a lid can then be of the most appropriate configuration. It has also already been found that, with the frustoconical configuration, any liquid which may have unintentionally escaped from the pack flows away outwardly so that the region of the lid remains substantially clean.
An apparatus for injection molding a plastics lid onto the tubular side walls is disclosed in German Offenlegungschrift No. 32 07 701, wherein the apparatus has an overall injection unit with a nozzle, an injection head member, an outside mold portion and a core which is movable relative to those components. With a continuous feed of the web-like material for the forming of the tube-like side walls, the apparatus disclosed in the above-identified specification can be used to inject a lid onto the side walls, at a high level of machine output. In such an arrangement, the core is disposed on the end of a mandrel which carries the tube. A mandrel wheel which is driven cyclically has mandrels which project radially in a plane at angular spacings from each other, and the outer mold portion which is disposed in opposite relationship to the core has mold parts which can be moved apart and towards each other, relative to the mandrel on at least two sides, to clear the circular movement path of the mandrel. By virtue of the rotary movement of the respective mandrel together with the mandrel wheel, the free end of the tube at which the plastics lid is to be injected thereonto is rotated into a position in alignment with an injection machine. In such an arrangement, the mandrels represent injection tool bottom portions, that is to say, core carriers, and the injection molding space if formed, towards the side by the outer mold parts, and upwardly by a head plate.
The outer mold parts cyclically move apart and provide space for the successive mandrels to be moved in and out with a rotary movement. The outer mold parts are pivoted about axes and move on circular arcs between the open and closed positions. The drive means is formed by draw rods which engage the support arms of the outer mold parts by way of ball joints.